Art of refining



Patented Oct. 13, 1942 ART OF REFINING Carl F. Cross and Edgar P. Grogg, Hammond, Ind., assignors to Sinclair Refining Company, New York, N. Y., a corporation of Maine No= Drawing.

Application January 5, 1939, Serial No. 249,455

4 Claims. (01. 196 -38) This invention relates to the refining of petroleum distillates and, more particularly, to the refining of petroleum distillates approximating kerosene in boiling range for the production of petroleum distillates substantially non-reactive with respect to metallic surfaces.

In the production of petroleum distillates suitable for use in the preparation of insecticides, and the like, where it is imperative that thedistillates do not corrode or discolor metallic surfaces, it is necessary to carry refining of these distillates to extremes for the removal of sulphur compounds which if permitted to remain would tend to react with metallic surfaces with which the distillates or compounds prepared from them might contact. Such refining has been accomplished heretofore by subjecting a suitable distillate to the action of a sodium plumbite or doctor solution, then to the action of an aqueous hypochlorite solution andthen to treatment with fuming sulphuric acid, followed by water washing and finally to contact with finely divided earthy material as a finishing operation. The treatment of the distillate with fuming sulphuric acid has necessitated as many as twenty or more separate water washings and each of these washing steps has required a considerable amount of time for agitation and subsequent settling. The resulting treated distillate, finished by contact with an earthy material such, for example, as clayor fullers earth, while substantially free from objectionable odor, is frequently reactive with respect to copper and other metals. It has been generally impossible to eliminate this characteristic when it appeared" even by the use of additional water washings and additional finishing with earthy material.

We have discovered that both the offensive odor and the corrosiveness of a distillate, a kerosene distillate for example, may be wholly eliminated by interposing between the water washing operation and the subsequent earth-finishing operation a special treatment of the distillate with steam and a relatively small amount of a solid alkaline compound such, for example, as sodium carbonate or caustic alkali. This treatment with an alkaline compound is carried out at an elevated temperature, advantageously at a temperature ranging upwards from about 200 F. to about the initial boiling point of the distillate under the conditions of the treat. The complete refining of a distillate of kerosene boiling range in accordance with our invention comprises, therefore, subjecting the distillate to the action of a doctor solution and then to the action of an aqueous hypochlorite solution, water washing to neutral, contacting the distillate with fuming sulphuric acid, water Washing to remove excess acid, contacting. the thus treated distillate with a solid alkaline compound and steam at an elevated temperature, water washing to neutral and subsequently treating the distillate with fullers earth. The finished product is substantially free from any tendency to corrode' or discolor copper or similar metals and is preeminently suitable for use in the preparation of insecticidal sprays and the like, or for any other purpose where a non-corrosive distillate of kerosene boiling range is particularly desirable.

As previously mentioned, the treatment of the washed acid-treated distillate with the alkaline compound is advantageously carried out at an elevated temperature; We have found that this may be accomplished with advantage by incorporating a relatively small proportion of alkaline compound in the acid-treated distillate and by then agitating, orrolling, the mixture with steam until the desired elevated temperature has been attained. Additional steam may then be introduced to maintain this elevated temperature for a period of time suflicient to reducethe reactivity of the distillate with respect to metallic surfaces to the desired degree. compound may be incorporated in the distillate in dry form with particular advantage although it may also be introduced as an aqueous solution.

The treating period at this elevated temperature is flexible and is governed by the extent to which it is desired to reduce the reactivity of the distillate. A period of one hour is usually sufficient for a distillate which has previously been treated in the usual way with a doctor solution, with a hypochlorite solution, and with concentrated sulphuric acid. The point at which the treatment with the alkaline compound has been completed may be readily ascertainedby means of the well-known mercury test. This mercury test is conducted by agitating a small sample of the distillate with mercury, the absence of any discoloration of the mercury being indicative of lack of reactivity of the distillate. The treatment with the alkaline compound may be stopped at any time after a negative mercury test is obtained.

The amount of alkaline compound used in accordance with our invention may vary within a substantial range. An amount equivalent to about one-quarter pound of sodium carbonate per barrel of distillate is generally satisfactory The alkaline vention is further illustrated in the following,

example which is given for the purpose of illustrating the practice of our invention:

After the usual treatment of a base for an insecticidal spray obtained froma kerosene distillate with a 21 B. doctor solution and'then with an aqueous solution of calcium hypochlorite followed by neutralization, the. oil'was subjected to the action of about 100 lbs. of 104.5% fuming.

sulphuric acid per barrel. Contact withthe acid was divided into nine successive treats with a contact time:of,one;half-hour:usingabout eleven pounds of acid per barrel in each .trea.t. The mixture of oil.andacid;was:allowed:to settle vfor about one. half-hour. betweentreats; and the acid sludge was. drawn ofi .after. each ;treat. The .acid treated oil .was. then given eight successive water washings using about 25% by volume of water for each washing, and the mixture of oiland water was blown with air during each washing for a period of about three minutes. Dry sodium carbonate was then added to the washed oil in an amount approximating one-third pound of sodium carbonate per barrel. The oil-sodium carbonate mixture was blown with live steam until the temperature of the mixture was about 210 F. and the blowing :then continued to maintain this temperatureuntil the mercury test on The: oil was a sample of the oil *wasnegative. then washed with a water-spray until neutral and blown brig-ht with air to remove entrained moisture. The blown oil was. finally treated with about two pounds per barrel of finely divided fullers earth for a period of about'one hour,

filteredand sent to storage. A strip of copper be carriedout satisfactorily by adding, caustic alkali, or the vlike, to the distillate in lieu of the sodium carbonate :referred to above. We prefer,

however, .to treat the distillate with dry-sodium' carbonate because the. handling of sodium carbonate-does not entail unusual precautions.

whereas the handling of solutions requires heated tanks and other special equipment to prevent the freezing of stock solutions during cold weather.

It is our present belief that the effectiveness of the special hot alkaline treatment of our invention is due to the fact that sulphonic acids, produced during the treatment of the distillate with fuming sulphuric acid when high temperatures are attained, are hydrolized by the steam to form free sulphuric acid which in turn is removed from the dlistillate by neutralization with rangeby treatment with fuming-sulphuric acid,

the improvement which comprises subjecting the acid treated distillate to treatment with steam and a relatively small amount of a solid alkaline compound at an elevated temperature below the initial boiling point of the. distillate under the conditions of treatment.

2. In the production of substantially non-reactive petroleumdistillates of kerosene boiling range by treatment with fuming sulphuric acid, the improvement which comprises subjecting the acid treated distillate to treatment with steam anda relatively small amount of a, solid alkaline compound at a temperature ranging upwards from about 200 F. to about the initial boiling point of the distillate under the conditions of treatment.

3- Inthe production of 'substantiallynon-reactive petroleum distillates of kerosene boiling range by treatment with fuming sulphuric acid, the improvement which comprises subjectingthe acid treated distillate to treatment'with steam and a relatively small amount ofsodium carbonate at. an. elevated temperature below the initial boiling point of the distillate-under the conditions of treatment. 7

4. In the production of substantially non-reactive. petroleum distillates of kerosene boiling range bytreatment with fuming sulphuric acid, the improvement which comprises subjecting the acid treated distillate to treatment with steam and a relatively small amount of caustic alkali at an elevated temperature below-'theinitial boiling point of the distillate under the conditions of treatment.

CARL F. CROSS;

EDGAR P. GROGG. 

